Road surfacing process



lit

UNITED STATES PATENT. OFFICE ROAD SURFACING PROCESS Harold B. Pullar,Chicago, Ill., assignor to Colprovia'Roads, Inc.,

poration of New York Rochester, N. Y., a cor- Serial No. 537,489

9 Claims.

This invention relates to a process of road construction and refersspecifically to a process whereby the component parts constituting thefinished road may be mixed and worked upon the road itself.

it has heretofore been proposed, particularly as embodied in the patentto Radcliffe No. l,655,240, to coat a. stone aggregate with bituminousmaterials, characterized 'in that the aggregate is first coated with aliquid binder having a melting point lower than is necessary to resistsummer heat, subsequently before or during the drying applying to thecoated aggregate while cold a powdered bituminous binder having amelting point higher than is necessary to resist summer heat andsubsequently lay the same as a macadamized road. However, Radcliifefound it necessary to perform all of the mixing operations previous tothe laying of the road, namely, the stone aggregate was first mixed withthe liquid binder in a conventional mixer and prior to the dryingthereof, powdered bituminous material was added and mixed with thecoated aggregate. This operation was contemplated to be performed remotefrom or adjacent the site of the road.

My invention is in one specific aspect directed to a method comprisingapplying to a gravel, broken stone or similar type of road or pavement,a liquid binder and immediately thereafter spreading over the surface alayer of stone or liquid binder and remove the objectionablecharacteristics thereof, and set the road so that it may be opened totraflic at once. All of said operations may be performed upon. the roaditself and consequently nothing but raw material need be transported tothe road side. I I

In carrying out my invention 1 may apply to a gravel, broken stone orother similar type of road or pavement, a quantity of road oil orresiduum oil, which is a heavy viscous oil produced from the refining orcracking of petroleum oil;

This oil may be sprayed on the road in any suitable manner and in.quantities of approximately of a gallon per square yard.

A layer of stone or gravel may be immediately spread over the oiledsurface in quantities of approximately '75 pounds per square yard. The

stone or gravel may then be mixed on the road by means of a roadmaintainer, drag or similar apparatus until the stone has beencompletely covered with the oil and presents a uniformly coated mam.

After the road has been treated as above described, I may apply to thesurface, by means of a suitable spreader or the like, a relatively thicklayer of powdered asphalt having a melting point or softening point offrom approximately 250 F., to 350 F., and a penetration of approximatelyto 7. Previous to the application of the asphalt the same may be groundor pulverized to a relatively finely divided state.

The ground, powdered or pulverized asphalt may be applied in quantitiesof approximately one-half pound, more or less per square yard. After theapplication of the asphalt the surface of the road may again besubjected toa mixing action by a road maintainer or any other suitabledevice which may mix and uniformly distribute the powdered asphaltthrough the mass of stoneand oil.

Due to the ailinity of the powdered asphalt to the oil, the asphaltrapidly disperses through the oil, absorbing the light oils and forminga gummy adhesive mixture which, under weather and traffic conditions,amalgamates into a uniform consistency, setting the stone or road metalinto a solid relatively homogeneous wearing surface.

The action of the powdered asphalt on the oil immediately absorbs thelight oils and removes the objectionable characteristics of the liquidoil, and sets the road for traflic at once.

It is to be understood, of course, that I do not wish to be limited tospecific quantities of materials described, inasmuch as the quantity ofoil used depends upon the thickness and grading of the stone, gravel orother road metal and the amount of asphalt used depends upon theconsistency of the. finished product desired; the more asphalt that isused the harder the road surface may become, and under somecircumstances as much as fifty percent of asphalt may be used in themixture.

It is also possible in some types of road surfacing to spreadthe asphaltover the surface and permit the same to disperse freely through the oilwithout the necessity of further mixing.

It may be found desirable to use a lighter or '50 heavier oil than thathereinbefore specified. Consequently, I do not wish to limit myinvention to the precise type of oil mentioned. As a lighter or heavieroil is used, the amount of asphalt may be adjusted accordingly; thelighter the oil the more asphalt it may require to produce the requiredconsistency; while conversely the heavier the oil a lesser-quantity ofasphalt may be found suilicient.

6 The-use of my invention makes it possible to treat a large mileage orroad surface in a most economical and simple manner by buildinga'uniform asphalt bituminous mat on the surface without theobjectionable oily mass obtained by 10 the use of road oil or othersimilar products. In addition, the handling of the materials and thetransportation thereof to the site of the road is facilitated and thecost thereof is reduced to .a minimum since nothing but raw materialsare transported to the road site.

I claim as my invention: a

i. A process cfmaking a bituminous road sur face which comprises thefollowing successive steps distributing a predetermined quantity ofrelatively heavy hydrocarbon liquid upon the surface of the road in thecold state, spreading 1 a predetermined quantity of mineral aggregateupon said coated surface and mixing said aggregate with the oil upon thesurface, distributing a. predetermined quantity of comminuted bituminousmaterial upon said mixed mass and mix-' ing said mass with saidbituminous material in the cold state.

2. The process of surfacing roads which conso sists in coating the roadwith a liquid asphaltic oil, applying thereon. a layer of aggregate, andthen spreading a layer ofcomminuted solid bituminous material at normaltemperatures and causing the latter to dissolve where it contacts withthe oil to form a homogeneous plastic binder between the road and theaggregate.

3. The process of surfacing roads which consists in coating the sub-baseof the road with .a liquid asphaltic oil, applying a layer of aggre- 40gate thereon and then spreading a layer of comminuted solid bituminousmaterial at normal temperatures and causing the latter to absorb the oilto form a homogeneous plastic binder between the aggregate and thesub-base without rendering tacky the surface area of said material.

4. The. process of surfacing roads which consists in coating thesub-base of the road with a liquid bituminous binder, applying a layerof in aggregate thereon, covering the road with a layer of comminutedsolid bituminous material at normal temperatures and causing said liquidbinder to be absorbed outwardly toward the surface of the layer ofmaterial.

3 5. The process of surfacing roads which consists in coating thesub-base of the road with a liquid asphaitic oil, applying a layer ofaggregate over the sub-base and oil, spreading over the road a layer ofcomminuted solid bituminous material at normal temperatures and capableof 5 absorbing said oil, forcing said bituminous material into the voidsof the aggregate and absorbing the oil in the bituminous material toform a binder in contact with the aggregate and the sub-base. l0

6. The process of surfacing roads which consists in coating the sub-baseof the road with a liquid asphaltic oil, applying a layer of aggregateover the sub-base and oil, spreading over the road a layer of comminutedsolid bituminous 15 material at normal temperatures and capable ofsolution in said oil, forcing said bituminous material into the voids ofthe aggregate and absorbing the excess of oil in the material withoutrendering the surface'of the latter viscous. 20

7. The process of surfacing roads which comprises coating the road witha liquid bituminous oil, applying thereon a layer of aggregate, and thenspreading a layer of comminuted solid bituminous material at normaltemperatures and 25 causing the latter to dissolve where it contactswith the oil to form a homogeneous plastic binder between the road andaggregate.

8. The process of surfacing roads which comprises, coating the road witha liquid bituminous 30 oil, applying thereon a layer of aggregate,mixing the aggregate and oil, and then spreading a layer of comminutedsolid bituminous material at normal temperatures and causing the latterto dissolve where it contacts with the oil to form 35 a homogeneousplastic binder between the road and the aggregate.

9. A method of making a bituminous road paving layer which comprisesmixing in situ aggregate and a bituminous binder of relatively lowstability and causing to be incorporated with the aggregate andbituminous binder of low stability while they are on the road a powderedbi-. tuminous material so that the powdered bituminous material iscommingled with the binder 5 of low stability and is distributedsubstantially throughout said aggregate, the resulting composition beingdisposed as a paving layer on the road and said powdered bituminousmaterial gradually amalgamating with the binder of low 60 stability toform a relatively stable .binder for the said paving layer substantiallythroughout its thickness.

HAROLD B. PUILAR.

